Up to now we have identified the carrier of Wilson's Disease (HLD) by a complicated study of radiocopper turnover kinetics. From this experience, it appears that a simpler means of identification is possible based on body retention of radiocopper. This is a proposal to develop a means of quantification of body retention of Cu.67. Preliminary combination turnover retention rates derived from excretion studies of Cu.67 clearly separate normals from HLD (heterozygotes or pre-clinical homozygotes). There is no other reliable method for separating such individuals. Cu.67 has not been adapted for this purpose in a long series. Identification of the carrier assists in the diagnosis of HLD itself, particularly in patients with borderline hepatic or neurologic findings. Moreover, carriers may not be as invulnerable as we have thought since some data suggest that alcoholism may affect them adversely. The kinetics of copper in the chronic alcoholic will also be tested. In addition, the carrier may be identified for genetic counseling. While in the general population the probability of one carrier finding another as a mate is low, probabilities rise considerably when a HLD family lives in a small community where kinships may become forgotten.